In today's marketplace, one of the products which has been proven to be most useful has been the aerosol spray can. Such cans have been used for an exceptionally wide variety of products including paint, hair sprays, whipped cream, etc.
It has recently been discovered that the spray cans known in the prior art have, unfortunately, often employed propellant gasses, mixed with the material to be sprayed, which are released to the atmosphere when the aerosol valve is actuated by the user. The initial conclusions from on-going testing are that the propellant gasses which are released to the atmosphere may be environmentally harmful. The current supposition is that the gasses will break down the earth's ozone layer, causing an increase in the sun's ultraviolet rays which will strike the earth and, possibly, thereby cause an increase in skin cancer.
Consequently, many legislative and administrative government bodies are considering and/or undertaking various actions which will result in banning the spray cans containing such propellants from the marketplace.
Other propellants which do not significantly pollute the environment often have undesirable side effects, such as unpleasantly cooling the object being sprayed.
Further, most of the present day aerosol cans are somewhat position sensitive. In other words, the product cannot be sprayed from the can at all when the can is tilted so that its axis is oriented at an angle greater than a certain degree with respect to vertical. In an extreme case, when a can is upside down, it normally will not spray any of the desired product at all, even though the can may be full. On the other hand, when the can is upside down and the aerosol valve is actuated, propellant gas will be expelled from the can. As more and more of the product has been sprayed from a can, the closer to vertical the axis of the can must be in order to allow continued spraying of the product.
As a result of these deficiencies in the prior art spray cans, many manufacturers are returning to the production of pump sprayers by means of which the consumer may actuate a pump to pressurize the interior of the container and cause the product to be sprayed through a valve. In many cases, the valve is contained in the pumping device so that, as the consumer actuates the pump with his index finger, for example, the product is sprayed through the valve.
Some pump sprayers do not include the valve as part of the pumping device so that a pressure can be built up within the container and the spray can be released at a later time on demand. However, in most cases those sprayers are relatively bulky and require several moving parts.
All of the pump sprayers are unsatisfactory for a number of reasons, including the fact that they are rarely operable to deliver anything but compresed air when the sprayer is in the upside down or inverted position. Further, since they depend upon an external force for application, and since the amount of pressurization is rather limited, they are limited in the amount of time during which the spary can be released from the container to that time during which force can be applied. For example, in those sprayers operated by squeezing a trigger, the spray can be released only as long as it takes to fully depress the trigger. Similarly, those sprayers operated by depressing a plunger can only spray during the time required to accomplish a full depression. Further, the force of the spray varies with the speed of squeezing the trigger or depressing the plunger and this may cause an undesirable variation in velocity of the spray from one stroke to the next, as well as during a single stroke.
Even with those pump sprayers which allow a pressure to be built up prior to release of the aerosol, the time during which the spray can be released is limited by the ability of the consumer to build up pressure within the container, usually requiring a good deal of his energy and time.
Accordingly, a need has developed for an aerosol spray device which can operate free from the limitations of the pump sprayers, as well as without creating or utilizing environmentally damaging gasses. Further, it is desirable to provide such a device which is not position sensitive, i.e., which will operate in the desired manner regardless of the orientation of the container.